The present invention relates generally to flameproof protected enclosures and specifically to Ex-d (aka Exd) protected enclosures.
The Ex-d flame protection standard is known. In certain explosion-prone environments, the external enclosure of flame-prone equipment must be designed to withstand an internal explosion so that the explosion cannot be transmitted through to the external environment. For instance, a reactor containing ultra-violet (UV) luminaires for water treatment placed in an explosion-prone environment requires that the reactor housing (aka envelope) be explosion proof. A flame or explosion originating from within the reactor (e.g. from the UV luminaire) must be contained within the envelope including being contained within inlet and outlet connection flanges.
Any devices (e.g. luminaires, probes, sensors) placed within the reactor are connected via Ex-d explosion proof housings. For instance, a UV luminaire for treating water flowing through a reactor is connected with an Ex-d lamp connector housing that will contain any flame originating within the reactor. However, such a flame must also be contained within the entire envelope.
The present invention uses the water within the reactor to contain explosions or flames by ensuring the reactor is full of water. The reactor is safe when full of water. All components are de-energized when the water level falls below a pre-established threshold. This can be accomplished using sensors to detect water level.
A sensor is utilized to confirm the reactor is full of water (in one embodiment, a sensor suitable for a Zone 1 environment is used). Upon sensing the chamber is not full, all power to the reactor is removed. One solution is to do this using as few mechanical components as possible. For instance, using a conductivity or flow switch connected to a contactor.
The sensors are operatively connected to the flame source utilizing conventional electrical cutoff circuitry to de-energize the flame source upon pre-established temperature and/or water levels.